JPH03501052A - Calibration system for coordinate measuring machines - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Calibration system for coordinate measuring machines field of invention The present invention relates to a coordinate measuring machine, and more particularly to a coordinate measuring machine that compensates for position-dependent errors in measured coordinate values. The present invention relates to a calibration system for coordinate measuring machines.

Background of the invention Coordinate measuring machines are used to inspect the dimensions of workpieces such as mechanical parts. The workpiece is hard It is fixed on a fixed stand, and the measurement probe can be moved up and down, and can also be used on horizontal surfaces. fixed to a dynamic ram. To measure the position of a point on a workpiece, The needle is brought into contact with the point and the X, y and zfi constant scale of the coordinate measuring machine is Ru. To measure the distance between two points, the two points are connected consecutively. The coordinates of both points are read and the distance is calculated from the coordinates.

State-of-the-art coordinate measuring machines include high-resolution measuring systems, electrical contact probes, power drives and components. It has improvements such as a computer-controlled drive device and computer collection and processing of data. ing.

The accuracy of a coordinate measuring machine is dependent on the inaccuracy of the scale or other measurement system and Limited by guideway imperfections that establish orthogonality of mechanical motion. to increase accuracy One approach is to simply improve the construction technique so that the error is reduced. The goal is to reduce system tolerances. However, as the required precision increases Error reduction is progressively more expensive. Another approach is through machine workload , y and a direct measurement of the two-point error. This approach is useful for large machines The huge amount of data that must be measured and the The time required makes it impractical. The third approach is in the form of parameters This is an error measurement. That is, if the set of error parameters is, for example, three mutually orthogonal Measured along the axis and stored for future use. Among the measured quantities? The X, y and 2 errors at the point are calculated from the parameter errors. The resulting error is subtracted from the scale reading to determine the actual workpiece coordinates.

The coordinate measuring machine has three sets of guideways for establishing probe movement. Ideally, this The motion along each of the guideways must result in linear motion only, and the scale The scale displayed in degrees will be equal to the linear displacement, but in reality, the scale error The guideway may not be completely straight, or it may not be possible to completely avoid twisting. 1 The original machine had six degrees of freedom that created errors during movement along each guideway. Ru.

For each direction of motion, there are three linear errors, Dx, Dy, and Dz; There are three rotational errors, Ax, Ay and Az. These six error parameters are machine Measurements can be made at multiple points along each direction of motion, and the results are 18 This becomes an error matrix with error parameters. From these 18 error parameter matrices, , the error can be calculated at a point in the measurand.

Various techniques have been used to measure parameter errors.

Laser interferometer technology is well known for high precision displacement error measurements. multi-station wave The technique of number interferometer is a U.S. patent granted to Baldwin on February 5, 1974. No. 3,790°284 for use in measuring straightness and rollover. has been done. Utilizing segmented photocells to detect stage tilt and yaw angles The system used is US Pat. No. 3, issued to Marcy on February 6, 1973. , 715.599. The four-quadrant angular motion sensor was introduced in October 1973. U.S. Patent No. 3,765,77, granted to Wi. It is disclosed in No. 2. One prior art approach to measuring parameter error is , “Mechanical Hulet-Paracard 5526A laser measurement described in "Calibration of Machine Tools" A fixed system is used. This system is transferable between machines, but only one machine Regular time is approximately 40 hours. Furthermore, different assemblies are required for each measurement and Assembly errors are difficult to avoid. 6 error parameters along each axis of machine motion The data measurement system was granted to Co., Ltd. on April 14, 1981. No. 4,261,107.

This system utilizes interferometric techniques to measure each of the error parameters. Therefore, a multi-frequency laser is used to measure the displacement perpendicular to the laser beam axis. Requires.

As a result, this system is complex and expensive. Furthermore, different fixed measurement configurations structure is utilized for each of the three axes of mechanical motion, which increases the complexity and complexity of this system. Adding more expenses.

Since the error parameters associated with a particular machine remain relatively constant in time, The calibration device can be attached to the machine and the calibration process can be performed in a short time. machine calibration, and even the calibration device can be removed for use with other machines. It is desirable to provide methods and machines for proper use.

Such calibration systems must provide highly accurate error measurements and require mechanical It must be easy to attach to the device and be easily removed after use. The single calibration method can be repeated as many times as necessary during the life of the machine.

A general object of the present invention is to provide an improved coordinate measuring machine.

Another object of the invention is a method for calibrating the position of a movable element in relation to a fixed element in a machine. and equipment.

Still another object of the invention is to provide a method and apparatus for improving the accuracy of a coordinate measuring machine. It is to be.

Yet another object of the invention is to reduce parametric errors associated with a movable element in relation to a fixed element. An object of the present invention is to provide a method and apparatus for measuring.

Still another object of the present invention is to provide an easily attachable and removable coordinate measuring machine calibrator. The goal is to provide a correct system.

Still another object of the present invention is to provide a method and apparatus for calibrating a coordinate measuring machine. Ru.

A further object of the invention is to detect parameter errors along each of the three directions of motion within a coordinate measuring machine. An object of the present invention is to provide a method and apparatus for accurately measuring.

R Satobe 1ka According to the invention, these and other objects and advantages are mutually compatible in at least two dimensions. Measuring parameters in a machine having a first element movable relative to a table and a table This is accomplished in an apparatus for measuring data errors. This device is attached to the first element is capable of attaching at least one reflector assembly to the table. directing a laser beam at the reflector assembly and reflecting it from the reflector assembly. detects the laser beam and generates error signals for displacement, straightness, tilt angle, yaw angle, and rollover. the laser measurement assembly to be produced and the laser measurement assembly to be measured in different orientations. attaching the reflector assembly to a table and attaching the reflector assembly to the first element in different orientations; 1. A reflector assembly and a laser measurement assembly comprising: Laser measurement assembly in which the emitted laser beam is reflected by a reflector assembly They are lined up in a row in each direction so that they can be returned to the grid. For each orientation, displacement, straightness , the tilt angle, yaw angle and rollover errors are multiple selected along the direction of the laser beam. Measured in position.

According to another aspect of the invention, the first Method for measuring parameter position errors in machines with elements and tables law is provided. The method includes: (a) positioning the reflector assembly in a first orientation; (b) attaching the laser measurement assembly to the reflector assembly; at least one laser beam in a first orientation aligned with the measurement assembly; is directed to the reflector assembly by the laser and reflected to the laser measurement assembly. (C) reflected back into the laser measurement assembly; Converts the returned laser beam into error signals for displacement, straightness, tilt angle, yaw angle, and rollover. storing the error signal; and (d) adding a first element to the method of the laser beam and the reflection. The reflector assembly is aligned with the laser beam and selected. and (e) reflect back to the laser measurement assembly and The detected laser beam is converted into error signals for displacement, straightness, tilt angle, yaw angle, and rollover. (f) storing a large number of selected new signals in the direction of the laser beam; repeating steps (d) and (e) above at the location; and (g) reflector assembly. (h) placing the laser on the first element in a second orientation perpendicular to the first orientation; Place the measurement assembly on the table with the reflector mounted in a second orientation perpendicular to the first orientation. (i) aligning and installing the assembly in a second orientation; C) to repeating steps (f).

In a preferred embodiment of the above method, a reflector assembly and a laser measurement assembly are provided. The assembly has a third orientation in which the first and second orientations are mutually orthogonal to the first and second orientations. and steps (C) to (f) are repeated for the third orientation. The result As a result, the error signals of displacement, straightness, heel angle, yaw angle and rollover are detected in the three directions of machine motion. are stored for each of them.

According to yet another aspect of the invention, the first elements are movable relative to each other in a selected direction. equipment for measuring measurement parameter errors in machines having a reflector assembly attachable to the first element; and a reflector assembly attachable to the first element; It can be mounted on a reflector assembly to direct multiple laser beams to the reflector assembly. A laser measurement assembly that senses the laser beam reflected from a reflector assembly. It is equipped with The reflector assembly and laser measurement assembly are selected a means for measuring displacement error along a direction and two directions perpendicular to said selected direction; and means for measuring straightness error. Straightness measurement method is reflector assembly The retroreflector attached to the beam and the laser beam from the laser measurement assembly. a means for directing the retroreflector and a laser measuring assembly located within the laser measurement assembly and divided into four quadrants; and a photodetector that detects the deviation of the reflected light from the center.

A reflector assembly and a laser measurement assembly are further provided.

Measure straightness and slope angles around two mutually orthogonal axes perpendicular to a selected direction means, the means includes a mirror mounted on a reflector assembly and a laser beam. means for directing a line from the laser measurement assembly to the mirror; The beam is divided into four quadrants, and the deviation of the reflected light from the center is sensed. It is equipped with a light sensor.

The reflector assembly and the laser measurement assembly are furthermore positioned near the selected direction. means for measuring the rollover error of the reflector assembly, the means being spaced apart by a prescribed distance; A pair of retroreflectors attached to the assembly and a laser measurement fixture a means for directing from the assembly to each of the retroreflectors and within the laser measurement assembly; a pair of sections each sensing the deviation of the reflected ray in a direction perpendicular to the positioned and selected direction; It is equipped with a light sensor. Rollover error is calculated using two lights separated by a specified interval. Proportional to the difference between the deviations sensed by the sensor.

According to another aspect of the invention, the first element and the first element are movable in a selected direction relative to each other. Measuring the rollover error around a selected direction on machines with A device is provided for attaching the device to the first element at a predetermined distance. Reflector assembly including a pair of separated retroreflectors and can be mounted on a table Means and selection for directing a pair of spaced apart collimated laser beams onto a retroreflector a pair of segmented beams that sense the displacement of each reflected ray in a direction perpendicular to the A laser measurement assembly including a photodetector and two light beams separated by a predetermined interval. and means for determining rollover error from the difference between the deviations sensed by the sensor. .

According to a further aspect of the invention, the first elements are movable relative to each other in a selected direction. and a table with two orthogonal planes perpendicular to the selected direction An apparatus is provided for measuring near-axis straightness and rollover errors. The device is a reflector assembly attachable to the first element; A mounted mirror and a laser beam that can be mounted on the table are directed towards the mirror. four quadrants that sense the angular deviation of the reflected laser beam from its center. a laser measurement assembly including a photodetector sectioned into a laser beam sensor; Straightness and yaw from the deviation sensed by the photocells separated by the distance between and means for determining the angle.

Brief description of the drawing A good understanding of the invention together with other objects and further objects, advantages and possibilities of the invention For this purpose, reference is made to the accompanying drawings.

FIG. 1 is a perspective view of a prior art coordinate measuring machine.

Figure 2 shows a coordinate measurement with the calibration system of the invention installed for y-axis calibration. A perspective view of the machine.

FIG. 3 shows a coordinate measurement with the calibration system of the invention installed for two-axis calibration. A perspective view of the machine.

FIG. 4 shows a coordinate measurement with the calibration system of the invention installed for X-axis calibration. A perspective view of the machine.

FIG. 5 is a schematic perspective view of the calibration system optics of the present invention.

FIG. 6 shows an interferometer used in the calibration system of the present invention for measuring displacement errors. A simple route map.

Figure 7 shows a simplified diagram of the optics used in the calibration system of the present invention for measuring straightness. A rough route map.

FIG. 8 is used in the calibration system of the present invention for measuring tilt and yaw angles. A simple schematic diagram of optics.

Figure 9 shows a simple diagram of the optics used in the calibration system of the present invention for measuring rollover. Rough route map.

Figure 10 shows the laser measurement assembly, reflector assembly and laser measurement assembly. Close-up side view of the fixture to which the reflector assembly is attached, with the reflector assembly on the y-axis. is shown with a phantom displaced along.

FIG. 11 is an enlarged front view of the reflector assembly.

Figure 12 shows the reflector assembly shown in the phantom at 12-1 in Figure 10. FIG. 12 is an enlarged front view of the laser measurement assembly taken along line 12;

FIG. 13 is a bottom view of the laser measurement assembly taken along line 13--13 in FIG. 12.

FIG. 14 is a cross-sectional view of the laser measurement assembly taken along line 14--14 of FIG. 12.

Figure 15 is an enlarged rear view of the laser measurement assembly taken along line 15-15 in Figure 14. In the figure, a cutaway view is provided to illustrate internal elements.

Figure 16 is like Figure 10! Laser measurement assembly along 116-16 installed FIG.

FIG. 17 is an enlarged partial cross-sectional view of the alignment eccentric cam of the laser measurement assembly.

A prior art moving bridge coordinate measuring machine is shown schematically in FIG. The measurement The machine is intended for measuring workpieces placed on a fixed machine table 12. Applicable The X, y and Z axes of the measuring machine are illustrated. Bridge 14 is the plan on table 12 It moves along the inner path 16 in the X direction. Carriage 18 is on the guideway on bridge 14 along the X direction.

The ram 20 has a probe 22 attached to its lower end and is connected via a bearing in the carriage 18. to move up and down. Between the bridge 14 and the table 12, between the carriage 18 and the bridge The scale system between the carriage 14 and between the ram 20 and the carriage 18 is arranged in three axial directions. Measure the coordinates of a point on the workpiece 10 that indicates the position of the moving element at the For this purpose, the probe 22 is brought into contact with this point. The probe 22 senses the contact and the system system computer and memorize the readings on the three scale systems. let An example of a moving bridge type coordinate measuring machine is manufactured by Brown and 5harpe. The calibration system of the present invention is mostly model 7101-2418 manufactured at the factory. can be used with prior art coordinate measuring machines.

Errors are caused by inaccuracies within the scale system and by guides running along each machine element. Imperfections within the internal tracts are introduced into the scale display power. Each mechanical element is When traveling in the direction, it is affected by an error having six components. These six components are will be described in relation to the movement of the bridge 14 in the directions. The six error components are also in the X direction is related to the movement of the carriage 18 in .

The first error component is a displacement error Dy along the direction of movement in the X direction. X direction and 2 directions The displacement errors Dx and Dz in the direction are commonly known as straightness; This is because these displacement errors Dx and Dz are the result of a guide path that is not completely straight. be. The remaining error components are rotational.

The rotation of the bridge 14 about the y-axis is commonly known as rollover Ay. X and 2 axis circumference The rotation of the bridge 14 is commonly known as the tilt angle Ax and the yaw angle Az, respectively. There is. To obtain a complete characterization of the machine using parameter errors, along the angular direction of motion Measurement of six error components at selected locations is required, resulting in 18 columns. It becomes an error matrix with .

The total error at any point in the measured capacitance is determined by the parameter as described below. calculated from the parameter error.

The calibration system of the present invention is a device that can be attached to a coordinate measuring machine for measuring 18 error components. The present invention also provides a method for performing error measurements. Shown in Figure 2 As shown, the calibration device includes a fixture 24 placed in a fixed position on the table 12. The calibration device can also be mounted on the fixture 24 in three different orientations for laser measurements. Assembly 26 is included.

The calibration device further includes a reflector assembly that can be mounted on the ram 20 in three different orientations. Contains 28.

In each of the three orientations, the laser measurement assembly 26 directs several laser beams. toward the reflector assembly 28. Laser measurement assembly 26 and reflector a Since the assembly 28 is aligned in each of the three orientations, the laser beam is reflected back to laser measurement assembly 26 and sensed. three In each of the orientations, the laser beam generated by the laser measurement assembly 26 is parallel to one of the directions of motion. In the orientation shown in Figure 2, the laser measurement The assembly 26 and the reflector assembly 28 are arranged so that the bridge 14 is moved in the y direction. The laser beam maintains alignment with the elements of reflector assembly 28 when are arranged so that In the orientation shown in Figure 3, the laser measurement assembly The reflector assembly 26 and reflector assembly 28 are arranged in such a way that the ram 20 is moved in two directions. the beams are aligned to maintain alignment with the reflector assembly 28. There is. Similarly, in the orientation shown in FIG. Reflector assembly 28 reflects the laser beam when carriage 18 is moved in the X direction. are aligned to maintain alignment with reflector assembly 28.

To calibrate the coordinate measuring machine, attach the fixture 24 to the table 12 as shown in Figure 2. It starts with attaching it. The fixture 24 is in place and aligned with the axis of the coordinate measuring machine. and fixed in place. Laser measurement head 26 is oriented for y-axis measurements. 0 reflector assembly placed over the position indicator on top of the mounted fixture 24. 28 is engaged with a position indicator on the laser measurement assembly 26 and mounted. is tightened with screws. The ram 20 is moved to the starting position and the reflex The body assembly 28 is secured to the body assembly 28 . The carriage 18 and ram 20 are used for these parts. It is interlocked with the guideway. For installation, the screws are removed and the bridge 14 is selected in the y direction. The spacing and number of zero calibration positions moved to the zero calibration position will depend on the size and timing of the coordinate measuring machine. The typical spacing of zero calibration positions is approximately 1 inch, depending on the rate of error change expected. Ru. For each position, the laser measurement assembly 26 and the scale system of the coordinate measuring machine are The output of the stem is read by the calibration computer 30. These outputs represent the y-axis parameters. processed to determine the parameter error.

For Z-axis error measurements, the laser assembly 26 is rotated in two directions as shown in FIG. A zero counter placed over the position indicator on the top of the fixture 24 oriented for measurement. Projectile assembly 28 is engaged with a position indicating device on laser measurement assembly 26. and then secured with the mounting screws. The ram 20 is moved to the starting position and It is fixed to the injection assembly 28. Bridge 14 and carriage 18 are based on these plans. It is intertwined with the inner path. The mounting screws are removed and the ram 20 is moved in the Z direction. be moved to the selected calibration position. The Z-axis parameter error is the X-axis error mentioned above. It is measured in a similar way to the measurement of differences.

For X-axis error measurements, the laser measurement assembly 26 is Placed on top of the position indicator on the top of the fixture 24 oriented for direction measurement 1 reflector assembly 28 engages a position indicator of laser measurement assembly 26. and secured with mounting screws. Ram 20 is moved to the starting position, and It is secured to a reflector assembly 28 . The bridge 14 and carriage 18 are It is interlocked with the guide route. The mounting screws are removed and the carriage 18 is direction to the selected calibration position. The parameter error on the X axis is the above It is measured in a similar manner to the measurement of the X-axis error.

A calibration computer 30 processes the error matrix into a standard format and stores it on a computer disk. Remember. When a coordinate measuring machine is used to measure a workpiece, the The computer loads the error matrix from the computer disk. on the workpiece When the coordinates of a point are measured, the coordinate measuring machine extracts the corresponding parameters from the error matrix. Find the meter error, calculate the x, y and 2 errors, and use these errors as corrections. Pull it.

The optical path diagram of the laser measurement assembly 26 and the reflector assembly 28 is shown in the fifth diagram. As shown in the figure. Laser 40 mounted within laser measurement assembly 26 supplies a laser beam 42, which is split several times into six parameters. Provides the beam necessary for measuring data errors. A portion of the laser beam 42 is used for displacement error measurement. displacement error measuring means 44, which includes a reflector assembly 28. to the laser measurement assembly 26 in conjunction with a retroreflector 46 mounted thereon. The actual displacement of the reflector assembly 28 is measured. laser measurement assembly The straightness measuring means 48 of 26 is coupled with a retroreflector 50 on the reflector assembly 28. Similarly, when the reflector assembly 28 is moved in the y direction, the The straightness deviations Dx and Dz of the reflector assembly 28 are measured. Laser measurement a The tilt angle and yaw angle measuring means 52 in the assembly 26 includes a reflector assembly. Rotation of reflector assembly 28 about the X and Z axes in conjunction with mirror 54 on 28 The rotation Ax and Az are measured respectively. Second straightness within laser measurement assembly 26 The retroreflector 58 mounted on the measuring means 56 and the reflector assembly 28 is It is used in combination with the first straightness measuring means 48 and the retroreflector 50, and the y-axis rotation The rotation or roll AM of the reflector assembly 28 is measured. The measurements shown in Figure 5 The fixed device is described in connection with FIGS. 6 to 9, and FIGS. The measurement means have been simplified for easy understanding.

In a preferred embodiment, laser 40 emits a beam 42 having a single wavelength. 0 In one embodiment of the invention, the laser plasma tube is a Melles grid type 05LH. It is a PP900 helium-neon laser. The empty length of the laser is warm-up resonance increases between the desired single wavelength mode and the undesired multi-wavelength mode. This occurs alternately between the two modes. The output of the laser 40 is controlled using a heater near the laser tube. It is stabilized in a single wavelength mode. The heater can sense the output beam of the laser 40. and controlled by. Laser 40 has a Brewster square window within its cavity. This cavity fixes the plane of polarization of the light beam 42. Ray 42 has a quarter wavelength (retarder) 60, but the retarder 6o directs its optical axis to the laser beam. It is set at an angle of 45 degrees with respect to the polarization plane of the 40 output. small part of laser beam The light beam is separated from the chief ray 42 by a partially silver mirror 62 and by a light-sensitive fine ray 64. is sensed. The output signal from the photosensitive miniature 64 controls the heater of the laser cavity. , which is a well-known function of the degree to which the output of the laser yields the desired signal wavelength mode. This is because that.

Lens 66 diffuses the chief ray reflected by mirror 62 and A downstream lens 68 collimates the light beams. This configuration distributes the light beam over long distances. decrease.

Beam splitter 70 divides the light beam from lens 68 into two split beams, i.e., a prism. 72 to the displacement measuring means 44 and straightness measuring means 48; line 71 and toward the inclination and yaw angle measuring means 52 and the second straightness measuring means 56. split into a second branched ray. Beam splitter 74 receives the first beam from prism 72. A portion of the branched light beam 71 is directed toward the displacement measuring means 44. through the beam splitter 74. The passing light beam is directed by prism 76 onto retroreflector 50 .

Then, it is reflected by the straightness measuring means 48. Beam splitter 78 splits the second beam A portion 73 is directed from the beam splitter 70 to the mirror 54. Reflection from mirror 54 The light beam passes through a beam splitter 78 towards the tilt and yaw angle measuring means 52. The rays are directed by prism 80 as rays 81 to retroreflector 58, and reflected to the second straightness measuring means 56.

The linear displacement error in the parameter error matrix is determined by the scale frequency and laser distance measurement. This is the difference between Laser distance measurements are made using an interferometer. preferred interferometer uses a single frequency laser with circular polarization as described above. But what distance Measurement interferometers can also be used.

In a distance measurement interferometer, the laser beam is divided into two parts: a measurement beam and a reference beam. It will be done. The length of the measurement optical path changes as the distance to be measured changes. Reference optical path The length of is fixed. The two rays are reflected and combined. These rays When phase combined, they strengthen and form bright stripes.

When these two rays combine out of phase, they cancel and form dark fringes. Ru. The number of changes in bright stripes and dark foreshortening is calculated as a measure of distance.

A preferred interferometer for distance measurement is shown in simplified form in FIG. two stripe pattern, one stripe pattern is photosensitive fine 82, and the other stripe pattern is photosensitive Made with 84 minute details. Beam splitters 86 and 88 are each integrally combined. Consists of two 90° prisms, one prism has a partially reflective coating on the joint. Covered on the sides. The coating is a mixed metal dielectric and has little effect on polarization. It is something without. The light beam 90 entering from the beam splitter 74 is the beam splitter 86 into two parts, the first part goes to a beam splitter 88; The second portion 91 goes to the retroreflector 46, where the beam from the beam splitter 86 divided into two parts by a light-sensitive fine splitter 88; , and the second portion is the return reflected by the retroreflector 46 , which goes to the photosensitive detail 84 . The light ray 93 is divided into two parts, the first part goes to the photosensitive detail 82 and the second The portion goes to the photosensitive detail 84, the retroreflector 46 is located within the reflector assembly 28. The other components shown in FIG. 6 that move with the mechanical ram 20 are laser measured. located within fixed assembly 26.

A fixed length reference beam is transmitted from the beam splitter 86 to the photosensitive precision 82. It passes through the sensor 88 and goes straight to the sensor 82. Variable length measuring beam from the splitter 86 to the retroreflector 46 and reflected back to the beam splitter 88. The beam is reflected by the beam splitter 88 onto the light sensitive spot 82 . Photosensitivity 84 The fixing length reference beam is transmitted from the beam splitter 86 and from the beam splitter 88. It is reflected and reaches the sensor 84. The photosensitive precision 84 has a variable length measuring beam. The beam goes from the beam splitter 86 to the retroreflector 46, and the beam is split by the retroreflector 46. It is reflected by the beam splitter 88 and goes straight to the detector 84. leading to.

The retroreflector 46 is preferably a cube at the prism corner; It can be thought of as a cut glass cube. Beam splitter 86 The light ray 91 entering from the corner is reflected three times from the back surface of the corner cube and is It is returned to the beam splitter 88 as a beam 93.

A characteristic of circularly polarized light is that whenever this polarized light is reflected, the hand turns over. I will be ignored. The reference light beam to the photosensitive fine 82 is not reflected, but the measurement light beam is reflected five times. It will be done. Thus, the two rays at the photosensitive detail 82 have opposite hand polarizations. . When the two circularly polarized rays of opposite hands combine, these combined rays become a single Forms a plane of polarized light. The plane of polarization is based on the phase relationship between the light beams.

As the retroreflector 46 moves, the measured path length of the light beam to the light-sensitive miniature 82 changes and the phase relationship changes. The person in charge changes. This rotates the plane of polarization around the optical path. polarizing filter 92 is placed between the beam splitter 88 and the photosensitive detail 82. The plane of polarization rotates. Then, the plane of polarization is aligned with the axis of the polarizing filter 92 twice per rotation, and the light is exposed to light. Pass through to minute 82. Also, twice every rotation, the plane of polarization is aligned with the axis of the polarizing filter 92. perpendicular to the object, and all light is blocked. In this way, the photosensitivity 82 is As the retroreflector 46 moves, bright and dark stripes are seen alternately. Polarizing filter 9 4 is placed in front of the photosensitive detail 84 and has the same effect.

The electrical output of the light sensitive particles 82 and 84 is proportional to the amount of light that strikes the light sensitive details. retroreflection When body 46 moves at a constant speed, the output is sinusoidal. Polarizing filter 92 The axes of and 94 are such that the two sinusoidal signals from photosensitive details 82 and 84 are at right angles. i.e. one signal is oriented to guide the other around l/4. Ru. When the retroreflector 46 moves in the - direction, the output of one photodetector is the same as that of the other photodetector. When the retroreflector 46, which guides the instrument to 90°, moves in the opposite direction, the same photodetector The output delays the other photodetector by 90°. This feature is used to determine the direction of movement. It is used for The number of cycles from each photodetector indicates the distance traveled and is stored in the calculator. The phase relationship between the two outputs indicates the distance traveled.

5, the displacement measuring means 44 further includes a prism 85 and a prism 87; The prism 85 directs the light beam 91 from the beam splitter 86 toward the retroreflector 46. , and the prism 87 converts the reflected light beam 93 from the retroreflector 46 into a beam splitter. Turn to 88. These prisms allow for tighter construction. Figure 5 shows In addition, between the polarizing filter 92 and the photodetector 82 and between the polarizing filter 94 and the photodetector 8 An optional lens 89 is shown between 4 and 4. The lens 89 is a photodetector 82.84 to increase the output signal.

Straightness is the linear error in the direction perpendicular to the intended direction of motion. Transfer For each calibration point along the direction of motion, there are two straightness errors in mutually orthogonal directions. There is a difference.

Straightness measuring means 48 and retroreflector 50 are illustrated in simplified form in FIG. . The laser beam 96 in the direction in which straightness is measured is reflected by the reflector 50. is reflected by the assembly 28 and passes along a parallel path as a beam 98 to the laser measurement assembly. The photodetector 102 is returned to the quarter-quadrant photodetector 102 within the assembly 26.

The retroreflector 50 is a corner cube or cat's eye stone that has two characteristics important for straightness measurements. It has certain symptoms. The first characteristic is.

Rays 96 and 98 are parallel despite the angular error in positioning the retroreflector. It is a certain thing. This means that mechanical rotation errors do not affect straightness measurements. means.

The second feature is that rays 96 and 98 are located at the vertices of the retroreflector when viewed along the y-axis. It is symmetrical with respect to .

For y-axis straightness measurements, the quarter-quadrant photodetector 102 is configured such that the bridge 14 When y=Q, the light ray 98 is concentrated on the orthogonal split lenses 105 and 107. It is positioned so that At other y positions, the vertical straightness error is D2. There is. This error Dz is caused by Move the distance @Dz. Due to the symmetry mentioned above, the return ray 98 moves vertically by 2Dz. do. In this way, the ray 98 is vertically displaced 2Dz from the horizontal splitting lens 105. Similarly, when there is a horizontal straightness error Dx, the corner vertical The vertices of the cube 50 move horizontally by Dx. The return ray 98 moves horizontally by 2Dx. , are horizontally displaced by 2Dz from the vertically split lens 107. Quarter quadrant optical analyzer 1 02 are four photodiodes 10 separated by dividing lines 105 and 107. 2a, 102b, 102c and 102d. Each photodiode is The light hits each photodiode with a proportional electrical output. Measuring vertical straightness Dz , the sum of the outputs from photodiodes 102c and 102d is is subtracted from the sum of the outputs from nodes 102a and 102b. The result is 4 photos Divide by the sum from all of the diodes to remove the effect of changes in beam intensity , this result is multiplied by a constant and converted to conventional length units. Similarly, horizontal true The directivity Dx is calculated from the sum of the outputs from the photodiodes 102b and 1°2d. Subtract the sum of the outputs from diodes 102a and 102c and get the four photoda It is determined by dividing the result by the sum of the outputs from all of the diodes.

With reference to FIG. 5, the straightness measuring means includes a prism 103, the prism 103 It is noted that the reflected beam 98 is redirected from the retroreflector 5o to the photodetector 102. Ru. Prism 103 allows for a simpler construction.

Rollover is a rotational error around the axis of motion. Considering again the motion along the y-axis, the rollover error The data that determines the vertical straightness along two lines spaced apart in the X direction. It is measured by making two measurements of the degree Dz. Regarding Fig. 5, one vertical straight The straightness measurement is handled by the first straightness measuring means 48 and the retroreflector 50, while The straightness measurement of measure 2 is processed by the second straightness measuring means 56 and the retroreflector 58. be done. Rollover measurements are illustrated in simplified form in FIG.

In the first straightness measuring means 48, the vertical straightness Dz is determined by the photodetector 102. and the photodetector 102 detects the vertical deviation of the return beam 98 as described above. Ru. Similarly, in the second straightness measuring means 56, the photodetector 104 is a retroreflector. Vertical straightness Dz2 is sensed by sensing the vertical deviation of the reflected light beam 106 from 58. do. When measuring rollover, only vertical displacement is of interest. therefore , photodetector 104 requires only two photodiodes. (Photodetector 10 2 requires 4 quadrants, since this is also used to measure verticality. . ) Alternatively, the top two photodiodes and the bottom two photodiodes The boards can also be wired together for photodetector 104. of each calibration position Therefore, the roll measured in arc degrees is calculated by subtracting the two vertical straightness measurements, the first and It is calculated by dividing by the distance C between the two straightness measuring means 48.56.

Therefore, rollover = (Dx2-Dz,)/C.

With reference to FIG. 5, the second straightness measuring means 56 includes a prism 108; The system directs light beam 106 from retroreflector 58 to photodetector 104 .

The yaw angle and the tilt angle are rotational errors about an axial direction perpendicular to the axis of motion. Horizontal (X and y) For calibration, the yaw angle is the rotation about the vertical axis and the tilt angle is the horizontal It is rotation around an axis. For vertical (Z) calibration, the yaw angle is calculated as a rotation around the edge in the y direction. is defined, and the tilt angle is the rotation around the edge in the X direction. Tilt angle and yaw angle measurement hand Stage 52 is shown in simplified form in FIG. The incident laser beam 1JA73 is splitter 78. The transmitted light beam 112 passes through the beam splitter 7 8 and used for the rollover measurement described above is a quarter wave. The reflected light beam passes through the elongated plate 116 and the beam splitter 78 to the quadrant photodetector 118. reflected back to the body.

The incident light beam 73 is circularly polarized. Beam splitter 78 has a strong effect on polarization. It has an all-dielectric partially reflective coating. This result shows that the transmitted ray 112 The reflected beam 114 is substantially parallel polarized and the reflected beam 114 is vertically polarized.

The quarter-wave plate 116 has its axis oriented at 45° with respect to the polarization plane of the reflected light 1a114. ray 114 to convert it to circularly polarized light. Reflection from mirror 54 is polarized light The returning light beam that passes through the quarter-wave plate 116 and returns to the polarization plane is However, due to the change in the hand of the mirror 54, the polarized light is now in the horizontal plane. be. Polarizing beam splitter 78 passes the totally reflected light beam to photodetector 118. make it look like

There are two reasons for the complex maneuver using polarized light. First, light ensure that all of the information is used. If beam splitter 78 is non-polarizing If so.

Half of the return beam from mirror 54 is reflected back along the path of beam 73.

Second, false reflections from the quarter-wave plate 116 and the measuring means 56 cause the photodetector 1 The aim is to prevent children from reaching the age of 18. The vertically polarized wave from the quarter-wave plate 116 The reflection is reflected back along the path of ray 73. The second straightness measuring means 56 The reflection is horizontally polarized and passed through beam splitter 78 along the path of ray 73. pass

To perform y-axis tilt and yaw angle measurements, photodetector 118 detects that bridge 14 is The arrangement is such that one reflected ray 120 is concentrated when =Q. Yaw angle error Az In another calibration position, the plane mirror 54 is rotated by Az about two vertical axes.

From the law of reflection, this means that if the angle between the incident ray and the reflected ray is 2Az, then the reflected The light beam 120 is horizontally displaced on the photodetector IIS. Displacement is determined in the same way as straightness. It is determined by The yaw angle Az in arc degrees is from the mirror 54 to the photodetector 118 is calculated as half the displacement at photodetector 118 divided by the distance . child The distance is determined when the bridge 14 adds the distance traveled to the calibration point with y=Q. This is the established fixation distance. In the case of the tilt angle Ax, the mirror 54 rotates around the horizontal X axis. Turn around. As with the yaw angle, this creates an angle of 2 between the incident and reflected rays. Ax, and the reflected beam 120 is vertically displaced on the photodetector 118. degree of arc The inclination angle Ax at is divided by the distance from the mirror 54 to the photodetector 118. is calculated as half the displacement at photodetector 118.

With reference to FIG. 5, the tilt angle and yaw angle measuring means 52 further include a prism 122 and The prism 122 includes a prism 124 that directs the beam 11 from the beam splitter 78. 4 to the quarter-wave plate 116, and the prism 124 to the beam splitter 7. A reflected beam 120 from 8 is directed to a photodetector 118.

A preferred embodiment of the calibration system of the present invention is illustrated in FIGS. 10-17. . The components of the laser measurement assembly 26 shown in FIG. 5 have an overall L-shaped cross section. contained within a housing 130 having a The laser measurement assembly 26 includes: for attachment to the fixture 24 in three different orientations as described in It is adapted to.

As best shown in FIG. 11, reflector assembly 28 is attached to support bracket 1. 32, the support bracket 132 is attached to retroreflectors 46.5o and 58. , further provides firm support to the mirror 54. Three tapered screws 134 are installed at the center of the assembly. Baka-roku 136 is provided for the single-thread screw 137, which fits the connector 134a (Fig. 12). The threaded thread 137 is threaded into the assembly width measurement assembly 28 and A reflector assembly 28 is secured to the laser measurement assembly 26. screw 137 The spring 139 and washer 140 on the shank maintain the desired spacing and tighten the single thread screw 134. is used to bias reflector assembly 28 against laser measurement assembly 26. . Ball 138 and clamp 141 hold reflector assembly 28 in the probe socket. used for fixing to the pole-ended stud 142 attached to the .

A top view of fixture 24 is shown in FIG. The fixture 24 is a frame having three sides. , the frame is rigidly attached to the table 12 and has three mutually orthogonal orientations. Attach the laser measurement assembly 26 in (Note: Figures 2 to 4) We have measures in place. The fixture 24 is placed directly on the machine table 12 and the datum It is tightened with a tool clamp 143. Clamp 1.43 is screwed to table 12 fixed by means of input. In connection with FIGS. 10 and 16.

Legs 150 of fixture 24 are tightened to table 12.

Three mounting bins 152 are provided for mounting the laser measurement assembly 26 in the X direction. The three mounting bins 154 are used to attach the laser measurement assembly 26 in the y direction. The three locators 156 are used to attach the laser measurement assembly in two directions. It is used to attach the bridge 26. Laser measurement assembly 26 (13th The locator 152a on the bottom of the figure) fits into the bin 152 during installation in the X direction. , and the y-direction installation. The fixed assembly includes a bin 156a (FIG. 12) that is Two of the 6 bins 156a that fit the cylinders 156 are attached to the side of the housing 130. is mounted on an upright arm 144.

The centering eccentric cam of the laser measurement assembly 26 is illustrated in FIG. B 145 is inserted into fixture 24 with sufficient clearance to allow rotation. Ru. Collar 146 is attached to the top of bin 145 and bin 154 is attached to the top of bin 145. 146 is offset from the center. When collar 146 is rotated, bin 15 4 moves in a circle to allow fine adjustment of the position of the laser measurement assembly 26. side The core cam arrangement may be held in a fixed position by a set screw after adjustment6. Typically, 3 In two installations, only one of the bins utilizes the eccentric cam arrangement of FIG.

The arrangement of elements within laser measurement assembly 26 is illustrated in FIGS. 13-15. It will be done. The arrangement of optical elements shown in FIG. 15 is designated by like reference numerals in FIG. Illustrated.

Laser 40 is mounted by means of bracket 160 and spring 162. Re A laser power supply 164 provides the necessary working voltage to the laser 40. transformer 16 6 supplies power for the laser heater as described above. The transformers 166 each have a solid state It has two output voltages coupled to relays 168 and 170. relay 168 and 170 disconnects power from the transformer 166 to the laser heater under the control of the computer 30. Replace. High voltage is used for rapid warm-up. low voltage is empty Also used for torso length control. With reference to FIG. 14, the reflector assembly 28 , 11114, the prism 122 is connected to the housing 130 by the seat 168. can be attached to. Prism 108.80.76.103.85 and 87 are the same Installed in any way. Thus, it is well applied for movements between different measurement positions A simple and robust laser measurement assembly is provided.

It will be understood that various changes and modifications are included within the scope of the invention. For example, the calibration system uses a fixed table and a bridge-type seat with a three-dimensionally movable ram. Although described in connection with a standard measuring machine, one calibration system has two movable relative to each other. Either or both of the 0 machine elements are equally applicable to any machine with 0 machine elements. For example, some types of coordinate measuring machines have a movable table. Use bull. Furthermore, reflector assembly 28 shall have only reflective elements. and all sensing elements are located within the laser measurement assembly 26. The eight calibration systems installed are such that one or more of the sensing elements is reflective. For example, the straightness measurement can be modified to be positioned on the body assembly 28. A constant light detector may be placed above reflector assembly 28. The disadvantage of this shape is the electrical physical coupling must be made for reflector assemblies that are often movable. There is no such thing. All laser beams are reflected by reflector assembly 28. 6 A further variation within the scope of the invention is when the laser Can be mounted in a fixed position and has a movable assembly to provide three light levels from the laser. along the measurement axis. Further deformations include inclination angle, yaw angle, straightness and The first step is to use a prior art interferometer to measure rollover.

The output signals from the photosensitive miniatures 82.84, 102.104 and 118 are For calculation and storage of parameter errors via conditioning circuitry Supplied.

When calculating the total error at any point in the measurand of a machine, the following symbol is used: used.

Dij=direction position error, A1k=angular position error, Pm=constituent molecule of the distance from the tip level point to the tip of the tip, ei - Axis constituent numerator of the total error at the tip of the probe, in Uni, i=x, y or 2= axis on which the position error is measured, j = x, y or 2 = axis direction of the error; k = x, y or 2 = axis around which the rotational error is measured, mwx, y or zm distance Orientation of dissociated constituent molecules.

Thus, for example, Dyz is the vertical (two-way) straightness measured along the y direction , while Ayy is the rollover of the y-direction ply measured along the y-direction.

Attach an axis system to each constituent molecule and write equations for transformations between the axis systems (conventional approach, rather than using a simpler approach. A simple approach is Determining the error constituent molecules for each parameter Firstly, the constituent molecules for each axis direction It is necessary to add The simple method is suitable because the main error is small. , so the second order (cosine) error is ignored. A bridge like the one shown in Figure 1. The errors at points x, y, z in edge-type machines are expressed in Table 1 according to this method. The rotation shown is around the machine axis rather than the guideway.

(Hereafter, extra white) Table 1 Bridge driving ODyy O scale measurement error in Bridge motion -Dyx OO horizontal straightness of Bridge motion Q O-Dyz vertical straightness of Py-Ayz-(x+Px)Ayz O-bridge rotation around the vertical axis Bu　0　(Z+Pz)　Ayz　-Py-Ayx ridge rotation around the X axis - (Z + Pz) Ayy O (X + Px) Ayy ridge rotation around the y-axis Carriage running Dxx OO scale of measurement error Note: X effect, Y effect, Z effect Carriage movement 0 - Dxy O horizontal straightness of Carriage movement 0 0 -Dxz vertical straightness of Px-Axz -Px-Axz O vertical straightness around the vertical axis -(Z+Pz)Axy OPx-Axy carriage rotation around the X axis O(Z+Pz)Axx -Px-Axx carriage rotation around the X axis Ram movement su OODzz kale measurement error Ram motion O-Dzy Q y straightness Record X effect Y effect -4 rainbow base Ram motion -Dzx OO X Straightness -Pz-kzy OPz-Azy ram rotation around the X axis OPz-Azx-Pyizx ram rotation around the X axis Py-Azz - Py-Azz O ram rotation around the X axis The columns of the table are summed to determine the total error.

ex=Dxx-Dyx-Dzx-(Z+Pz)Axy1Py-Axz-(Z+ Pz) Ayy+Py-Ayz-Pz-Azy+Py-Azzey=Dyy-Dz -Dxy-(X+Px)Ayz+(Z+Pz)Ayx-Px-Azz+ pz -AZX-PX-Axz+ (Z+Pz)Axx ez=Dzz-Dxz-Dyz-Py-Azx+px-Azy-Py-Axx+ Px-Axy-Py-Ayx+ (X+Px)Ayy To correct for mechanical errors, ex is subtracted from the X scale display power and ey is the Y scale. It is subtracted from the scale display power, and ez is subtracted from the Z scale display power.

It is generally difficult or impossible to measure parameter errors directly along the machine axis It is. If measurements are made along other axial lines, then the following equation is The basic principle for deriving the zero equation used to calculate the parameter error is All parameter errors are zero at the initial stage and all measured values are on the measurement line. The value measured by the zero calibration system, which is zero at the zero travel position, is machined. When sending to the mechanical axis, a first-order symbol is used.

B” = distance or angle measured during mechanical calibration, first star placed in x, y or 2 d, h, V, y, I) or r. represents the type of measurement.

"d" represents a linear displacement measurement.

h'' represents the horizontal straightness measurement; in the Z axis, h represents the X direction.

"V" represents vertical straightness measurement; in two axes, V represents the y direction.

y” represents the yaw angle measurement; in the X and y axes, the yaw angle is the angular rotation about the vertical axis . The Z axis is an angular rotation around the X axis.

np'' stands for tilt angle measurement; in X and y, the tilt angle is around the horizontal line perpendicular to the measurement line. is the angular rotation of 2 is the angular rotation around the X-axis.

"r" stands for auxiliary straightness measurement for rollover determination; in the X and y axes, the measurement is vertical; It is direct. In the Z axis, the measurement is in the y direction.

P range is from the tip level point in error measurement (such as the top of a retroreflector). It is a component of the distance to the measurement point. The first star is by X, y or 2 The second star, which is replaced and represents the measurement line, is replaced by x, y or 2. represents the direction of the constituent molecules.

Oll is the coordinate of the line used for measurement. defined by two such coordinates The line shown is the reference path of the tip level point during a set of measurements. Stars are x, y or 2 to represent the direction of the coordinates.

C is a component of the distance between two straightness measurement lines in rollover measurement. the symbol above The values of displacement error Dij and rotational error Aik are calculated as follows.

Axx=(Bx r-Bxv)/C Axy=Bxp Axz=Bxy Ayx=Byp AVV=(Byv-Byr)/C Ayz=Byy Az　x=Bz　p Az　y=Bz　y Az　z=　(Bz　r-Bzv)/CDxx, =X, -Bxd+　(07,+ PX　Z)Ax　y　-P　x　y　A　x　z D x y = B x h - X - A yz - P x x - A X 7 ．． +(Oz+Pxz)Axx Dxz=Bxv-Pxy-Axx+Pxx-Axyx-Ayy Dyx=Byh-(○z+Pyz)Ayy+Pyy-Ayz Dyy=Y-Byd+ (Ox+Pyx)Ayz-(Oz+Pyz)Ayz Dyz=Byv-Pyy -Ayx+ (Ox+Pyx)Ayy Dzx=Bzh-Z-Axy-Z-Ayy-PZ7. -Azy 10Pzy-Az z Dzy=B7. V + Z -A, y x -P z x -A z　z　＋　Pzz　°　Azx＋Z　゛　Axx DZ7-=Z-Bzd+Pzy-Azx-Pzx-Azy Preferred implementation of the invention Although the examples have shown and described what is currently possible, various changes and modifications are attached. The preferred embodiments without departing from the scope of the invention as defined by the claims It will be obvious to those skilled in the art that this can be done within.

Submission of translation of written amendment (Patent Law Article 184-8) May 1990? Japanese duck Yoshi, Commissioner of the Patent Office 1) Takeshi Moon 1. Display of patent application PCT/US 88103855 2. Name of the invention Calibration system for coordinate measuring machines 3. Patent applicant Address: North Kingesta, Rhode Island, USA 02852 Precision Park (no address) Name: Brown & Sharp ・Manufacturing/Residency: 2-2-1 Otemachi, Chiyoda-ku, Tokyo Otemachi Building 206 Ward 5. Date of submission of written amendment The scope of the claims 1. a first element and a table movable relative to each other in at least two dimensions; A device for measuring position error in a machine, comprising: a reflector assembly attachable to the first element; and a reflector assembly attachable to the table. with the ability to direct at least one output laser beam in the selected measurement direction and sensing the at least one laser beam reflected from the reflector assembly; a laser measurement assembly that generates a position error signal representative of a position error of the first element; and mounting the laser measurement assembly on the table in different orientations. and attaching the reflector assembly to the first element in different orientations, A reflector assembly and the laser measurement assembly are connected to the at least one output. The emitted laser beam is directed to the laser measurement assembly by the reflector assembly. means adapted to be aligned in each of said orientations for reflection back; It will be equipped with. Said device.

2. The position error measuring device according to claim 1, wherein the mounting means comprises: +4. m) a position error signal for each selected position in said first, second and third orientation; into a matrix of parameter errors along three orthogonal directions. The position error measuring method according to item 13.

15, n) for a constant position of said first element its total position error is expressed as said parameter; 0) calculation of the position of the first element relative to the table of the machine; obtain the scale display frequency, and calculate the first total error to the scale table of the machine; subtracting from the reading to obtain a corrected position of the first element.

The position error measuring method according to claim 14, further comprising:

16. having a first element and a table movable relative to each other in a selected position; In a machine that

A reflector assembly that can be attached to the first element and a reflector assembly that can be attached to the table. Laser measurements that detect multiple laser beams reflected from the reflector assembly at an assembly, the reflector assembly and the measurement assembly comprising: 19. Selection of the reflector assembly and the first element along the selected direction; 18. The parameter error measurement device of claim 17, further comprising means for moving to a selected position. Place.

20. A first element and a second element movable in at least two directions relative to each other. A parameter position error measuring device in a machine having: a first subassembly attachable to said first element and a first subassembly attachable to said second element; a second sub-assembly; A second sub-assembly directs a plurality of laser beams to the first sub-assembly. the first subassembly includes means for directing the plurality of laser beams; the calibration assembly further includes means for receiving the plurality of radiation lines; the parameter position error along the at least two movement directions in response to the light beam; sensing means for providing a position error signal for display, said parametric error comprising: displacement errors in three mutually perpendicular directions and rotational errors about said three mutually perpendicular directions; including the difference, and.

The plurality of laser beams are continuously parallel to the at least two moving directions. said sensing means detects said position error signals for said at least two directions of movement. for attaching said first and second sub-assemblies as given in Said apparatus comprising means.

21. A first element and a second element movable in at least two directions relative to each other. A parameter position error measuring device in a machine having: a first calibration assembly attachable to the first element; a second calibration assembly attachable to the second element; measuring a change in distance between the first and second calibration assemblies in a selected direction; a plurality of laser beams between interferometer means and said first and second calibration assemblies; lateral and rotational relative movement of the first and second calibration assemblies as occurs; means positionally sensitive to said first and second beams in response to said position sensitive laser beam; a beam position sensing means for sensing relative lateral and rotational movement of the calibration assembly of FIG. said first and second elements in response to the outputs of said interferometer means and said beam position sensing means; means for calculating a parameter position error between; The device comprising:

22. A first element and a second element movable in at least two directions relative to each other. A parameter position error measuring device in a machine having: a first subassembly attachable to said first element and a first subassembly attachable to said second element; a second sub-assembly; The sub-assembly of 2 directs the at least one laser beam in a selected direction to the means for directing the first sub-assembly to the first sub-assembly; the assembly includes means for receiving said at least one laser beam; The positive assembly further comprises, in response to the at least one laser beam, the at least one laser beam. both give a position error signal indicating the parametric position error along the two directions of movement. the parameter error in three mutually orthogonal directions; including a displacement error and a rotation error about the three mutually orthogonal directions, and the at least one laser beam is continuous with respect to the at least two movement directions; the sensing means for the at least two directions of movement are parallel to each other; the first and second sub-assemblies are arranged to provide a position error signal; said device, comprising means for attaching said device.

23. said attachment means are attached to said table at a preselected position; and means for mounting said laser measurement assembly in each of said specific orientations. 23. The parametric position error measurement device of claim 22, comprising a fixture comprising:

24, said mounting means includes said laser measurement assembly and said first and second sub-assemblies; - includes means for mounting the assembly in three mutually orthogonal orientations, thereby providing three 23. The parameter according to claim 22, wherein a set of parameter errors along mutually orthogonal directions is measured. Lameter position error measuring device.

25, the first and second sub-assemblies are a first means of measuring displacement error; step and second means for measuring straightness in two directions orthogonal to said selected direction. and measure the tilt and yaw angles representing the rotation about an axis perpendicular to the selected direction. and third means for measuring a rollover error representative of rotation about the selected direction. 25. The parameter position error measuring device according to claim 24, comprising the means of item 4.

26, said machine for measuring the position of said second element relative to said first element; a scale device for moving in the selected direction of movement; means for calculating a matrix of parameter errors corresponding to selected positions along the the total error for any position of said first and second elements in response to the parameter error; calculating the difference and subtracting the total error from the displayed power of the scale device. and means for providing accurate location information. Meter position error measuring device.

27, wherein said second measuring means is attached to one of said sub-assemblies; a retroreflector that directs the laser beam from the other of the subassemblies. means for directing the reflected light from said retroreflector into quadrants; 25. A photodetector for sensing deviation of the laser beam from its center. The parametric position error measuring device described in .

28, wherein said third measuring means is attached to one of said sub-assemblies; and directing a laser beam from the other of said sub-assemblies to said mirror. means for dividing the laser beam into quadrants and reflecting from said mirror from the center thereof; 26. The parameter position error according to claim 25, further comprising a photodetector that detects a deviation. measuring device.

29, said fourth measuring means are spaced apart by a prescribed distance and said A pair of retroreflectors attached to one of the assemblies and one individual laser beam a hand directing a line from the other of said sub-assemblies to each of said retroreflectors; a step, perpendicular to the selected direction and perpendicular to a line drawn between the pair of retroreflectors; a pair that senses the deviation of each laser beam reflected by the retroreflector in the direction of a light sensor divided into sections, and the rollover error is determined by the specified distance. Claim proportional to the difference between the deviations sensed by the two separated photodetectors The position error measuring device according to item 5.

international search report

Claims (33)

[Claims] 1. a first element and a table movable relative to each other in at least two dimensions; A device for measuring position error in a machine, comprising: a reflector assembly attachable to the first element; and a reflector assembly attachable to the table. with the ability to direct at least one output laser beam in the selected measurement direction and sensing the at least one laser beam reflected from the reflector assembly; a laser measurement assembly that generates a position error signal representative of a position error of the first element; and mounting the laser measurement assembly on the table in different orientations. and attaching the reflector assembly to the first element in different orientations, The reflector assembly and the laser measurement assembly are arranged such that the emitted laser beam reflected back to said laser measurement assembly by a reflector assembly. and means adapted to be arranged in a row in each of the different orientations. Device. 2. 2. The position error measuring device according to claim 1, wherein the attachment means and the laser measurement assembly is attached to the table in a and a mounting device including means for mounting in each of said different orientations. 3. The attachment means connects the laser measurement assembly and the reflector assembly. including means for mounting in three mutually orthogonal orientations, thereby providing three mutually orthogonal orientations; 2. The position error measuring device according to claim 1, wherein a set of parameter errors along the alignment is measured. . 4. the machine is a coordinate measuring machine and the first element is a ram movable in three dimensions; The position error measuring device according to claim 3. 5. The laser measurement assembly and the reflector assembly measure displacement errors. and measuring straightness in two directions orthogonal to the selected direction. a second means, an inclination angle and an offset representing rotation about an axis orthogonal to the selected direction; third means for measuring a yaw angle and a rollover error representing rotation about said selected direction; 4. The position error measuring device according to claim 3, further comprising fourth means for measuring. 6. each selected position along the selected measurement direction in response to the position error signal; 6. The method of claim 5, further comprising means for calculating a matrix of parameter errors corresponding to the position. Position error measurement device. 7. The machine comprises three mutually orthogonally movable bridges, a carriage and a ram. a coordinate measuring machine having a position of the bridge, the carriage and the ram; 7. The position error measuring device according to claim 6, further comprising a scale device for monitoring. 8. The bridge, the carriage and the ram are adjusted in response to the parameter error. Calculate the total error for a given position and calculate the total error from the scale device reading. 8. The location error according to claim 7, further comprising means for subtracting the location error to provide accurate location information. Difference measuring device. 9. a retroreflector, wherein the second measuring means is attached to the reflector assembly; and means for directing a laser beam from the laser measurement assembly to the retroreflector. and the reflected light from the center divided into quadrants within the laser measurement assembly. The positional error sure device according to claim 5, further comprising a photodetector that detects a line shift. . 10. the third measuring means comprises a mirror attached to the reflector assembly; , means for directing a laser beam from the laser measurement assembly to the mirror; The laser measurement assembly is divided into quadrants and the reflected light from the center. The position error measuring device according to claim 5, further comprising a photodetector that detects a line shift. . 11. said fourth measuring means are spaced apart by a predetermined distance and said reflector A pair of retroreflectors attached to the assembly and a pair of retroreflectors attached to the assembly and directing each laser beam to the means for directing the measurement assembly to each of said retroreflectors; Each reflection in a direction perpendicular to the direction and perpendicular to the line drawn between the pair of retroreflectors a pair of segmented beams within said laser measurement assembly for sensing beam deviation; a sensor, wherein the rollover error is detected by two sensors separated by the defined distance. 6. The position according to claim 5, which is proportional to the difference between the displacement sensed by the photodetector. Error measuring device. 12. a first element and a table movable relative to each other in at least two dimensions; a) a reflector assembly on a first element with a first reflector orientation; attaching and positioning the first element in a first selected position; b) Place the laser measurement assembly on the table in line with the reflector assembly. At least one laser beam is directed toward the laser measurement aperture with a first laser beam oriented towards the reflector assembly along the measurement direction selected by the assembly. and reflected back to the laser measurement assembly. a step of attaching them so that they are arranged in a row on each of them; c) at least one laser beam reflected back to said laser measurement assembly; sensing the line to determine the displacement, straightness, and tilt angle of the first element relative to the table; providing a position error signal representing a yaw angle and roll position error, and storing said error signal; The process of d) said reflecting said first element and said reflector assembly in said selected direction; the body assembly is aligned with the at least one laser beam; a step of moving the e) said at least one laser reflected back to said laser measurement assembly. the displacement, straightness, and inclination angle of the first element relative to the table by sensing a light beam; providing a position error signal representing a yaw angle and roll position error, and storing said error signal; The process of f) for a plurality of selected positions in the direction of the at least one laser beam; d) and e); and g) attaching the reflector assembly to the first element. a step of attaching the second reflector to the h) placing said reflector assembly on said table in line with said reflector assembly; a second laser orientation step; i) repeating steps c) to f) for the second orientation; Measure the parameter error in the relative position of the first element and the table, comprising: how to. 13. j) attaching said reflector assembly to said first element in a third reflector orientation; a step of making the orientations of the first, second and third reflectors orthogonal to each other; k) placing said laser measurement assembly on said table in line with said reflector assembly; the first, second and third reflectors are aligned with each other. a step of making it orthogonal to 1) repeating steps c) to f) for the third orientation; The position error measuring method according to claim 12, further comprising: 14. m) a position error signal for each selected position in said first, second and third orientation; The method further includes the step of converting the parameter error into a matrix of parameter errors along three mutually orthogonal directions. 14. The position error measuring method according to claim 13. 15. n) for a given position of said first element its total position error is expressed as said parameter; o) calculating the first total error from the scale display degree of the machine; subtracting from a number to obtain a corrected position of the first element; The position error measuring method according to claim 14, further comprising: 16. a first element and a table movable relative to each other at selected positions; In a machine that a reflector assembly attachable to the first element and attachable to the table; Laser measurements that detect multiple laser beams reflected from the reflector assembly at an assembly, the reflector assembly and the measurement assembly comprising: a first means for measuring a position error along a selected direction; The straightness is measured in two orthogonal directions, and the straightness is measured in two orthogonal directions. a retroreflector for directing a laser beam from the laser measurement assembly to the retroreflector; and means for directing the laser beam into four quadrants within said laser measurement assembly. a second means comprising a photodetector for sensing the deviation of the reflected light beam from the center; Measure the inclination angle and yaw angle of two mutually orthogonal axes perpendicular to the direction in which the a mirror attached to a reflector assembly and a mirror attached to the reflector assembly; means for directing the mirror from the assembly; It is divided into two quadrants and is equipped with a photodetector that detects the deviation of the reflected light from the center. and measuring a rollover error representing rotation in the vicinity of the selected direction, and attached to said reflector assemblies spaced apart by a fixed distance. a pair of retroreflectors and separate laser beams from the laser measurement assembly. means for directing said retroreflector to each of said retroreflectors; said sensing the deviation of each reflected ray in the direction orthogonal to the line drawn between the reflectors. and a pair of segmented light sensors within the laser measurement assembly. two photodetectors, the rollover error being separated by the defined distance; relative to the first element and the table proportional to the difference between the deviation sensed by A device that measures parameter errors in position. 17. The laser measurement assembly further includes a laser for generating a laser beam and the laser. The laser beam is measured by the first measuring means, the second measuring means, the third measuring means and the fourth measuring means. 17. The parameter according to claim 16, comprising means for dividing into portions fed to the determining means. Data error measuring device. 18. The laser beam splitting means causes the reflected portion to face the beam splitter surface. including means for polarizing the laser beam so that it is vertically polarized; polarized parallel to the plane of the beam splitter, where the third measuring means further polarizes the beam by 90°. includes a quarter-wave plate that rotates the plane of polarization of the reflected beam at Rather than the returning light beam being reflected back towards the laser, a polarizing beam splitter The parameter error measuring device according to claim 17, which passes through. 19. selecting the reflector assembly and the first element along the selected direction; 18. The parameter error measurement device of claim 17, further comprising means for moving to a selected position. Place. 20. a first element and a table movable relative to each other at selected positions; In a machine that a pair attachable to said first element and spaced apart by a prescribed distance; a reflector assembly including a retroreflector; a pair of spaced apart parallel laser beams mountable to said table; means for directing said retroreflector to said retroreflector; A device that senses the deviation of each reflected ray in a direction that is perpendicular to the line drawn between the retroreflectors. a laser measurement assembly including a pair of segmented photodetectors; The difference between the deviations detected by the two photodetectors separated by a specified distance. means for determining a rollover error from the difference; and A device that measures rotation error. 21. Each of the divided photodetectors is located at a position that does not deviate from the laser beam. 13. The method of measuring rollover error according to claim 12, comprising a pair of photovoltaic cells separated by a dividing line. equipment. 22. a first element and a table movable relative to each other at selected positions; In a machine that a retroreflector attachable to said first element and including a retroreflector attached thereto; a projectile assembly that is attachable to the table and that retroreflects the laser beam; It includes a means for directing it toward the body and a four-quadrant photodetector that senses the deviation of the reflected beam from its center. The laser measurement assembly and the relative intensities of the reflected beams received from each quadrant of the photodetector. means for determining straightness error from degrees; A device for measuring the relative straightness of two orthogonal axes perpendicular to a selected direction, comprising: . 23. a first element and a second element movable in at least two directions relative to each other; An apparatus for measuring parameter position errors in a machine having a first calibration assembly attachable to the first element; attachable to the second element to direct a plurality of laser beams to the first calibration assembly; a second calibration assembly directed towards the the parameters along the at least two movement directions in response to the plurality of laser beams; sensing means for providing a position error signal representative of the meter position error; The error is displacement error in three mutually orthogonal directions and rotation around the three mutually orthogonal directions. a sensing means including an error; The first and second calibration assemblies are connected to the plurality of laser beams by the at least two calibration assemblies. the sensing means is continuously parallel to the at least two movement directions; means for mounting to provide said position error signal for a direction of movement; The said device. 24. Parameters in a machine having a first element and a second element movable relative to each other A device for measuring meter position error, the device comprising: a first calibration assembly attachable to the first element; a second calibration assembly attachable to the second element; measuring a change in distance between the first and second calibration assemblies in a selected direction; interferometer means and relative lateral and rotational movement of said first and second calibration assemblies; means for positionally sensitively generating a plurality of laser beams; transversely of the first and second calibration assemblies in response to the position sensitive laser beam; and a beam position sensing means for sensing rotational relative movement; said first and second elements in response to the outputs of said interferometer means and said beam position sensing means; means for calculating a parameter position error between; The device comprising: 25. a first element and a table movable relative to each other in at least two dimensions; A device for measuring position error in a machine that a reflector assembly attachable to the first element; and a reflector assembly attachable to the table. with the ability to direct at least one output laser beam in the selected measurement direction and sensing the at least one return laser beam reflected from the reflector assembly; and generate a position error signal representing a relative position error between the first element and the table. a laser measurement assembly; Mount the laser measurement assembly on the table in different orientations and attaching the reflector assembly to the first element; and the laser measurement assembly, wherein the at least one emitted laser beam reflected back to said laser measurement assembly by a reflector assembly. means arranged in a row in each of the different directions; The device comprising: 26. a first calibration assembly attachable to the first element; attachable to said second element for directing at least one laser beam in a selected direction; a second calibration assembly directed towards said first calibration assembly at said before moving along said at least two directions of movement in response to at least one laser beam; sensing means for providing a position error signal representative of the parameter position error; The meter error is the displacement error in three mutually orthogonal directions and the circumference error in the three mutually orthogonal directions. a sensing means including a rotational error of said first and second calibration assemblies; In both cases, one laser beam is continuously parallel to the at least two movement directions. and said sensing means detects said position error signals for said at least two directions of movement. means for attaching the a first element movable in at least two directions relative to each other and a second element comprising: Apparatus for measuring parameter position errors in machines having elements. 27. said attachment means being attached to said second element at a preselected location; and means for mounting said second calibration assembly in each of said different orientations. 27. The parametric position error measurement device of claim 26, comprising a fixture. 28. Said mounting means mount said first and second calibration assemblies in three mutually orthogonal directions. a set of parameters along three mutually orthogonal directions; 27. Parameter position error measurement device according to claim 26, wherein meter error is measured. 29. a first means for the first and second calibration assemblies to measure displacement errors; a second means for measuring straightness in two directions perpendicular to said selected direction; A first step that measures the tilt and yaw angles representing rotation about an axis perpendicular to the selected direction. and a fourth means for measuring rollover error representing rotation around the selected direction. 29. The parametric position error measurement device of claim 28, comprising a step. 30. a schedule in which the machine measures the position of the second element relative to the first element; a control device, wherein the device further adjusts the motion in response to the position error signal. Computes the matrix of parameter errors corresponding to the selected position along the selected direction. and means for constant positioning of said first and second elements in response to said parameter error. and subtracting said total error from said scale device reading. 27. A parameter position as claimed in claim 26, further comprising means for providing precise location information. Position error measuring device. 31. said second measuring means is attached to one of said calibration assemblies; a reflector, and directing a laser beam from the laser measurement assembly to the retroreflector. and means for dividing the laser measurement assembly into quadrants from the center thereof. 30. The parameter according to claim 29, further comprising a photodetector that detects a shift in reflected light rays. data position error measuring device. 32. The third measuring means is a mirror attached to one of the reflector assemblies. a mirror, and means for directing a laser beam from the laser measurement assembly to the mirror. and is located within the laser measurement assembly and is divided into quadrants and from the center thereof. 30. The parameter according to claim 29, further comprising a photodetector that detects a shift in reflected light rays. data position error measuring device. 33. said fourth measuring means are spaced apart by a predetermined distance and said reflector A pair of retroreflectors attached to the assembly and directing each laser beam to the means for directing the laser measurement assembly to each of the retroreflectors; drawn between the pair of retroreflectors perpendicular to the selected direction within the assembly. A pair of segmented light sensors that sense the deviation of each reflected ray in the direction perpendicular to the line the rollover error is separated by the prescribed distance; 30. The parameter of claim 29, which is proportional to the difference between the deviation sensed by the sensor. Meter position error measuring device.